Butt is prob moving due to foot placement. If the angle of the hip is correct to the foot, no way for the butt to come up. Those are pretty strong reps really. We have talked about how you normally do really well with reps, and not as much with heavier weight. I think next week we will ramp up the sets again, and use 250 as the final weight. Going to try and find a video for you to take a look at for foot placement. Mike Womack has a good one.